This invention relates to a method and apparatus for legal intercept monitoring of a cellular telephone modem (CTM) device. More particularly, the invention relates to a system incorporating a CTM-to-TTY/TDD converter and a Call Content Delivery Unit (CCDU) to facilitate the monitoring of calls made from a CTM device.
While the invention is particularly directed to the art of legal intercept monitoring of a CTM device, and will be thus described with specific reference thereto, it will be appreciated that the invention may have usefulness in other fields and applications. For example, the principles of the invention may be used in any application where monitoring of a call from a device having a different messaging format is desired.
By way of background, United States law provides that law enforcement agencies may monitor the telephone content of telephone conversations when appropriate court orders are issued. In this regard, any telephone user may be monitored. However, present technologies do not allow for all types of calls to be monitored. In particular, calls that originate or terminate with cellular telephone modem (CTM) devices which support Telephone Devices for the Deaf (TDD) cannot be monitored using present standards or technology.
More specifically, under traditional United States wireless standards, TDD devices support a method called teletype for TDD (TTY/TDD). However, GSM and UMTS wireless standards support CTM for support of TDD devices in Europe and elsewhere. These GSM and UMTS wireless standards, though, are now being implemented in the United States.
To illustrate the conventional technologies, reference is first made to FIG. 1. FIG. 1 illustrates an exemplary network having a bearer (or voice) path for a non-CTM, non-monitored call. More specifically, the network 10 is illustrated and it includes a mobile switching center (MSC) 12 having an MSC server 14 in communication with a packet backbone network 16. The packet backbone network 16 communicates with a media gateway 18 which, in turn, communicates with radio access network (RAN) 20 and public switched telephone network (PSTN) 22. The normal bearer path for such a call includes bearer path segment A and bearer path segment F. Because the call is non-CTM and non-monitored, there is no need for accommodating either of these special cases with respect to the bearer path. Calls that originate (or terminate) at either end of the network are processed using well known techniques.
Referring now to FIG. 2, an exemplary network 50 is illustrated. Within the network 50, a bearer path for a non-CTM, monitored call, is shown. More particularly, an MSC 52 is provided which includes an MSC server 54 and a packet backbone network 56. The packet backbone network 56 communicates with a media gateway 58 which is in communication with a radio access network (RAN) 60 and a public switched telephone network (PSTN) 62.
Also included within the MSC 52 is a call content delivery unit (CCDU) 70 which is used to collect call content for purposes of monitoring. Such monitoring techniques are well known in the field of law enforcement. The CCDU 70 may also reside in a location remote from the MSC 52, in which case appropriate communication paths are established so that the call monitoring and/or collection functions can be accomplished. In the configuration shown, however, the bearer path includes portion A which connects the wireless device to the media gateway and a portion D which allows delivery of call content to and from the CCDU 70. The call content collected by the CCDU 70 is also delivered to and from the PSTN 62 on bearer path portion E, which leads to the media gateway, and bearer path portion F which leads out to the public switch telephone network. Because this is a non-CTM call, no special treatment for CTM devices is required in this configuration. The format of the call content is the same for all portions on the bearer path. Calls that originate (or terminate) at either end of the network are processed using well known techniques.
Referring now to FIG. 3, the bearer path for a CTM, non-monitored call is illustrated within an exemplary network 100. More particularly, the network 100 includes a mobile switching center (MSC) 102 having an MCS server 104 and a packet backbone network 106. The mobile switching center (MSC) 102 also includes a media gateway 108 which communicates with a radio access network (RAN) 110 and a public switched telephone network (PSTN) 112. Notably, the MSC 102 also includes a converter 120 which converts call content in CTM format to call content in TTY/TDD format in manners that are well known to those in the field. It should be understood that, like the CCDU 70 of FIG. 2, the converter 120 may reside in a location remote from the MSC 102. In such a case, communication paths are preferably established between the MSC 102 and the converter 120 so that appropriate conversion functions may be carried out by the converter. In operation, for example, for a call originating in the radio access network 110 that is in CTM format, call content is received by the media gateway 108 on bearer path portion A and delivered to the converter 120 on bearer path portion B. The format of the call content on portions A and B is in CTM format. Of course, the converter 120 converts the CTM formatted call content to TTY/TDD format and delivers the call content on bearer path portion C back to the media gateway 108. The media gateway 108 then delivers the call content to a destination network such as PSTN 112, via bearer path portion F. Calls originating with the PSTN 112 and terminating with the RAN 110 can be likewise processed.
In FIGS. 1-3, the media gateway and MSC server are illustrated as being implemented on separate hardware platforms. However, it should be appreciated that the media gateway and MSC server may also be implemented on the same hardware platform. The differences between such implementations are well known to those skilled in the art.
As illustrated by FIGS. 1-3 and the above description of technology, it is apparent that there is no current technology that allows for monitoring of a call that originates or terminates in CTM format.
The present invention contemplates a new and improved method and apparatus for legal intercept monitoring of a cellular telephone modem (CTM) device that resolves the above-referenced difficulties and others.